Transfer method of functional region, LED array, LED printer head, and LED printer

Abstract

A method includes arranging a bonding layer of a predetermined thickness on at least one of a first functional region bonded on a release layer, which is capable of falling into a releasable condition when subjected to a process, on a first substrate, and a region, to which the first functional region is to be transferred, on a second substrate; bonding the first functional region to the second substrate through the bonding layer; and separating the first substrate from the first functional region at the release layer.

What is claimed is: 
     
       1. A method comprising:
 arranging a first bonding layer of a first predetermined thickness at a region on a second substrate to which a first functional region bonded on a release layer on a first substrate is to be transferred, the release layer being capable of falling into a releasable condition when subjected to a process; 
 bonding the first functional region to the second substrate through the first bonding layer; 
 separating the first substrate from the first functional region at the release layer; 
 forming a predetermined unevenness on a region on the second substrate, other than the region to which the first functional region is to be transferred, and 
 wherein plural functional regions, including the first and a second functional regions, are bonded on the release layer on the first substrate, and the unevenness is formed on a region on the second substrate, corresponding to the second functional region remaining on the first substrate. 
 
     
     
       2. The method according to  claim 1 , wherein the first substrate has a light-transmitting property, the release layer includes a material subject to decomposition or decrease in bonding strength by irradiation of light, and the separating the first substrate includes performing irradiation of light to a portion of the release layer between the first functional region and the first substrate. 
     
     
       3. The method according to  claim 1 , wherein the first and the second functional regions are arranged on the first substrate at a first predetermined inter-distance, regions each of which is to be connected to the first functional region transferred to the second substrate are arranged on the second substrate at a second predetermined inter-distance. 
     
     
       4. The method according to  claim 3 , wherein relations 1 to 3 are satisfied
     l <or= L   (relation 1)
 
     W>w   (relation 2)
 
     W+S>w+s   (relation 3)
 
 
       where w is the width of each of the first and second functional regions on the first substrate, l is the length of each functional region, s is the distance between the functional regions, W is the width of the region to be connected to the first functional region transferred to the second substrate, L is the length of the region on the second substrate, and S is the distance between the regions on the second substrate. 
     
     
       5. The method according to  claim 1 , further comprising arranging a second bonding layer of a predetermined thickness on at least one of the second functional region remaining on the first substrate, and a region, to which the second functional region is to be transferred, on the second substrate or a region, to which the second functional region is to be transferred, on a third substrate; bonding the second functional region to the second substrate or the third substrate through the bonding layer; and a separating the first substrate from the second functional region at the release layer. 
     
     
       6. The method according to  claim 5 , further comprising forming a predetermined unevenness on a region on the second or third substrate, other than the region to which the second functional region is to be transferred. 
     
     
       7. The method according to  claim 5 , wherein the first substrate has a light-transmitting property, the release layer includes a material whose decomposition or decrease in bonding strength occurs by irradiation of light, and the seventh step includes a step of performing irradiation of light to a portion of the release layer between the second functional region and the first substrate. 
     
     
       8. The transfer method according to  claim 5 , wherein the release layer includes a material whose decomposition or decrease in bonding strength occurs by heating or cooling, and the seventh step includes a step of heating or cooling the release layer. 
     
     
       9. The method according to  claim 5 , wherein the second or third substrate includes a fourth functional region, and the second functional region is bonded to the fourth functional region through the bonding layer. 
     
     
       10. The method according to  claim 1 , wherein the second substrate includes a third functional region, and the first functional region is bonded to the third functional region through the bonding layer. 
     
     
       11. The method according to  claim 1 , wherein, the first functional region is bonded to the second substrate through the bonding layer which is a second release layer capable of falling into a releasable condition when subjected to a process, and
 further comprising: arranging a second bonding layer of a second predetermined thickness on at least one of the first functional region on the second substrate, and a region, to which the first functional region is to be transferred, on a fourth substrate; bonding the first functional region on the second substrate to the fourth substrate through the second bonding layer; and separating the second substrate from the first functional region at the second release layer. 
 
     
     
       12. The method according to  claim 1 , wherein the first or second functional region on the first includes a compound semiconductor layer, and the first substrate is prepared by preparing a substrate structure in which the first or second functional region is formed by providing an etching sacrificial layer, the compound semiconductor layer, the release layer, and the first substrate on a compound semiconductor substrate in this order, a first groove is formed in the compound semiconductor layer, a penetrating second groove is formed at least one of the first substrate and the compound semiconductor substrate so that the penetrating second groove is connected to the first groove, and separating the compound semiconductor substrate from the substrate structure by bringing an etchant into contact into the etching sacrificial layer through the first groove and the penetrating second groove to etch the etching sacrificial layer. 
     
     
       13. The transfer method according to  claim 1 , wherein the first or second functional region includes a compound semiconductor layer, and the first substrate is prepared by: forming an interface separation layer on a seed substrate by a hetero epitaxial growth, forming the compound semiconductor layer on the interface separation layer, bonding the seed substrate with the interface separation layer and the compound semiconductor layer to the first substrate through the release layer, and separating the first substrate with the release layer and the compound semiconductor layer from a composite structure, utilizing the interface separation layer, to obtain the first substrate with the compound semiconductor layer. 
     
     
       14. A method comprising:
 arranging a first bonding layer of a first predetermined thickness at a region on a second substrate to which a first functional region bonded on a release layer on a first substrate is to be transferred, the release layer being capable of falling into a releasable condition when subjected to a process; 
 bonding the first functional region to the second substrate through the first bonding layer; 
 separating the first substrate from the first functional region at the release layer; 
 forming a predetermined unevenness on a region on the second substrate, other than the region to which the first functional region is to be transferred, and 
 wherein the release layer includes a material subject to decomposition or decrease in bonding strength by heating or cooling, and the separating the first substrate includes heating or cooling the release layer.